diff --git a/.github/actions/prepare/action.yml b/.github/actions/prepare/action.yml
index f2c2687a..42aabf1c 100644
--- a/.github/actions/prepare/action.yml
+++ b/.github/actions/prepare/action.yml
@@ -45,7 +45,7 @@ runs:
       uses: actions/cache/restore@caa296126883cff596d87d8935842f9db880ef25 # v5.1.0
       with:
         path: /mnt/kryptik/sources
-        key: sources-v2-${{ hashFiles('sources.lock') }}
+        key: sources-v3-${{ hashFiles('sources.lock') }}
         # A changed lock restores the previous set and fetches only what is
         # new; every file is still hashed against the lock.
         restore-keys: ${{ inputs.sources == 'fetch' && 'sources-' || '' }}
@@ -55,6 +55,9 @@ runs:
       run: |
         make sources
         ./tools/prune-sources.sh
+        # The signatures too, so the set this job saves is the one CI's
+        # signature gate reads from disk; this pass is not the verdict.
+        ./tools/verify-signatures.sh > /dev/null 2>&1 || true
 
     # Saved as soon as the set is verified, not when the job ends: a job that
     # fails later would otherwise fetch the lock's new files again next time.
@@ -62,4 +65,4 @@ runs:
       uses: actions/cache/save@caa296126883cff596d87d8935842f9db880ef25 # v5.1.0
       with:
         path: /mnt/kryptik/sources
-        key: sources-v2-${{ hashFiles('sources.lock') }}
+        key: sources-v3-${{ hashFiles('sources.lock') }}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8a123589..b678181e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -133,15 +133,19 @@ jobs:
         uses: actions/cache/restore@caa296126883cff596d87d8935842f9db880ef25 # v5.1.0
         with:
           path: /mnt/kryptik/sources
-          key: sources-v2-${{ hashFiles('sources.lock') }}
+          key: sources-v3-${{ hashFiles('sources.lock') }}
           restore-keys: |
             sources-
 
+      # The signatures are fetched here too, into the set the cache keeps:
+      # the gate below then reads them from disk instead of asking sixty
+      # hosts again on every run. What this pass says is not the verdict.
       - name: Fetch and verify the sources
         if: steps.sources.outputs.cache-hit != 'true'
         run: |
           make sources
           ./tools/prune-sources.sh
+          ./tools/verify-signatures.sh > /dev/null 2>&1 || true
 
       # Not from a pull request: its cache is scoped to its merge ref, so every
       # one whose lock differs from main's would keep a whole copy of its own.
diff --git a/tools/verify-signatures.sh b/tools/verify-signatures.sh
index cd9968d9..317182f1 100755
--- a/tools/verify-signatures.sh
+++ b/tools/verify-signatures.sh
@@ -714,6 +714,13 @@ verify_detached() {
         report "$name" no-signature-upstream "no ${suffix} published beside the tarball"
         return
     fi
+    # A host can answer a busy runner with a page in place of the file: what
+    # came back is not kept, and the file is asked for once more.
+    if ! is_pgp_signature "$sig"; then
+        rm -f "$sig"
+        [[ "${KRYPTIK_SIGCHECK_SELFTEST:-0}" == "1" ]] || sleep 5
+        quiet_fetch "$sigurl" "$sig" || rm -f "$sig"
+    fi
     if ! is_pgp_signature "$sig"; then
         rm -f "$sig"
         warn "${name}: the published ${suffix} is not an OpenPGP signature"